Relation $R = \{(a, b): a < b\}$ is defined on the set of real numbers. Then $R$ is . . . . . . .

Which one of the following relations on $R$ is an equivalence relation?

The number of reflexive relations on a set with $4$ elements is equal to

Let $A = \{0, 1, 2, 3, 4, 5\}$. Let $R$ be a relation on $A$ defined by $(x, y) \in R$ if and only if $\max\{x, y\} \in \{3, 4\}$. Then among the statements $(S_1)$: The number of elements in $R$ is $18$,and $(S_2)$: The relation $R$ is symmetric but neither reflexive nor transitive:

Let $A = \{1, 2, 3, 4\}$ and $R = \{(1, 2), (2, 3), (1, 4)\}$ be a relation on $A$. Let $S$ be the smallest equivalence relation on $A$ such that $R \subset S$. If the number of elements in $S$ is $n$,then the value of $n$ is:

Let $A = \{1, 2, 3, 4\}$ and $R = \{(2, 2), (3, 3), (4, 4), (1, 2)\}$ be a relation on $A$. Then $R$ is: